Phosphatidylinositol is one of a number of phospholipids found in cell membranes, and which participate in intracellular signal transduction. Cell signaling via 3′-phosphorylated phosphoinositides has been implicated in a variety of cellular processes, e.g., malignant transformation, growth factor signaling, inflammation, and immunity (Rameh et al (1999) J. Biol Chem. 274:8347-8350). The enzyme responsible for generating these phosphorylated signaling products, phosphatidylinositol 3-kinase (also referred to as PI 3-kinase or PI3K), was originally identified as an activity associated with viral oncoproteins and growth factor receptor tyrosine kinases that phosphorylate phosphatidylinositol (PI) and its phosphorylated derivatives at the 3′-hydroxyl of the inositol ring (Panayotou et al (1992) Trends Cell Biol 2:358-60). Phosphoinositide 3-kinases (PI3K) are lipid kinases that phosphorylate lipids at the 3-hydroxyl residue of an inositol ring (Whitman et al (1988) Nature, 332:664). The 3-phosphorylated phospholipids (PIP3s) generated by PI3-kinases act as second messengers recruiting kinases with lipid binding domains (including plekstrin homology (PH) regions), such as Akt and PDK1, phosphoinositide-dependent kinase-1 (Vivanco et al (2002) Nature Rev. Cancer 2:489; Phillips et al (1998) Cancer 83:41).
The PI3 kinase family comprises at least 15 different enzymes sub-classified by structural homology and are divided into 3 classes based on sequence homology and the product formed by enzyme catalysis. The class I PI3 kinases are composed of 2 subunits: a 110 kd catalytic subunit and an 85 kd regulatory subunit. The regulatory subunits contain SH2 domains and bind to tyrosine residues phosphorylated by growth factor receptors with a tyrosine kinase activity or oncogene products, thereby inducing the PI3K activity of the p110 catalytic subunit which phosphorylates its lipid substrate. Class I PI3 kinases are involved in important signal transduction events downstream of cytokines, integrins, growth factors and immunoreceptors, which suggests that control of this pathway may lead to important therapeutic effects such as modulating cell proliferation and carcinogenesis. Class I PI3Ks can phosphorylate phosphatidylinositol (PI), phosphatidylinositol-4-phosphate, and phosphatidylinositol-4,5-biphosphate (PIP2) to produce phosphatidylinositol-3-phosphate (PIP), phosphatidylinositol-3,4-biphosphate, and phosphatidylinositol-3,4,5-triphosphate, respectively. Class II PI3Ks phosphorylate PI and phosphatidylinositol-4-phosphate. Class III PI3Ks can only phosphorylate PI. The main PI3-kinase isoform in cancer is the Class I PI3-kinase, p110α. (U.S. Pat. No. 5,824,492; U.S. Pat. No. 5,846,824; U.S. Pat. No. 6,274,327). Other isoforms are implicated in cardiovascular and immune-inflammatory disease (Workman P (2004) Biochem Soc Trans 32:393-396; Patel et al (2004) Proc. Am. Assoc. of Cancer Res. (Abstract LB-247) 95th Annual Meeting, March 27-31, Orlando, Fla., USA; Ahmadi K and Waterfield M D (2004) “Phosphoinositide 3-Kinase: Function and Mechanisms” Encyclopedia of Biological Chemistry (Lennarz W J, Lane M D eds) Elsevier/Academic Press), and oncogene mutations in PI3 kinase (Samuels et al (2004) Science 304:554). Oncogenic mutations of p110 alpha have been found at a significant frequency in colon, breast, brain, liver, ovarian, gastric, lung, and head and neck solid tumors. PTEN abnormalities are found in glioblastoma, melanoma, prostate, endometrial, ovarian, breast, lung, head and neck, hepatocellular, and thyroid cancers.
The initial purification and molecular cloning of PI3 kinase revealed that it was a heterodimer consisting of p85 and p110 subunits (Otsu et al (1991) Cell 65:91-104; Hiles et al (1992) Cell 70:419-29). Since then, four distinct Class I PI3Ks have been identified, designated PI3K α (alpha), β (beta), δ (delta), and ω (gamma), each consisting of a distinct 110 kDa catalytic subunit and a regulatory subunit. More specifically, three of the catalytic subunits, i.e., p110 alpha, p110 beta and p110 delta, each interact with the same regulatory subunit, p85; whereas p110 gamma interacts with a distinct regulatory subunit, p101. The patterns of expression of each of these PI3Ks in human cells and tissues are also distinct. In each of the PI3K alpha, beta, and delta subtypes, the p85 subunit acts to localize PI3 kinase to the plasma membrane by the interaction of its SH2 domain with phosphorylated tyrosine residues (present in an appropriate sequence context) in target proteins (Rameh et al (1995) Cell, 83:821-30; Volinia et al (1992) Oncogene, 7:789-93).
The PI3 kinase/Akt/PTEN pathway is an attractive target for cancer drug development since such agents would be expected to inhibit proliferation, reverse the repression of apoptosis and surmount resistance to cytotoxic agents in cancer cells. PI3 kinase inhibitors have been reported (Yaguchi et al (2006) Jour. of the Nat. Cancer Inst. 98(8):545-556; U.S. Pat. Nos. 7,173,029; 7,037,915; 6,608,056; 6,608,053; 6,838,457 ; 6,770,641; 6,653,320; 6,403,588; WO 2006/046031; WO 2006/046035; WO 2006/046040; WO 2007/042806; WO 2007/042810; WO 2004/017950; US 2004/092561; WO 2004/007491; WO 2004/006916; WO 2003/037886; US 2003/149074; WO 2003/035618; WO 2003/034997; US 2003/158212; EP 1417976; US 2004/053946; JP 2001247477; JP 08175990; JP 08176070). Wortmannin analogs have PI3 kinase activity in mammals (U.S. Pat. No. 6,703,414; WO 97/15658).
Thienopyrimidine compounds of Formulas I and II have p110 alpha binding, PI3 kinase inhibitory activity and inhibit the growth of cancer cells (WO 2006/046031; US 2008/0039459; US 2008/0076768; US 2008/0076758; WO 2008/070740; WO 2008/073785.

Formula I compound, GDC-0941 (Genentech Inc.), is a selective, orally bioavailable inhibitor of PI3K with promising pharmacokinetic and pharmaceutical properties (Belvin et al, American Association for Cancer Research Annual Meeting 2008, 99th: April 15, Abstract 4004; Folkes et al, American Association for Cancer Research Annual Meeting 2008, 99th: April 14, Abstract LB-146; Friedman et al, American Association for Cancer Research Annual Meeting 2008, 99th: April 14, Abstract LB-110).
Combinations of anti-cancer pharmaceutical therapeutics administered simultaneously or sequentially in a dosing regimen are now common in cancer treatment. Successful combination therapy provides improved and even synergistic effect over mono-therapy, i.e. pharmaceutical treatment limited to one drug. Combination therapy for the treatment of hyperproliferative disorders such as cancer has been studied, including antitumor activity of erlotinib in combination with capecitabine in human tumor xenograft models (Ouchi et al (2006) Cancer Chemother. Pharmacol. 57:693-702), and erlotinib in combination gemcitabine and cisplatin in non-small cell lung cancer (NSCLC) tumor xenograft models (Higgins et al (2004) Anti-Cancer Drugs 15:503-512). Preclinical research has been the basis for prediction of clinical stage synergy of anti-cancer pharmaceutical therapeutic combinations including capecitabine and taxanes for the treatment of breast cancer (Sawada et al (1998) Clin. Cancer Res. 4:1013-1019). Certain doses and schedules of combination therapy of capecitabine and taxane can improve safety without compromising efficacy (O'Shaughnessy et al (2006) Clin. Breast Cancer April 7(1):42-50). Synergistic effects of anti-fungal combinations in vitro have been correlated with clinical stage synergy (Steinbach et al (2003) Clin. Inf. Dis. October 1; 37 Suppl 3:S188-224).